Pneumatic stamping plant.



H. C. BEHR. PNEUMATIG STAMPING PLANT. APPLICATION IILBD .TUNE 30, 1909.1 O34 863, Patented Aug. 6,1912. 3 SHEETS-SHEET 1.

1 4 F lill!!! H. C. BEHR.

PNEUMATIC STAMPING PLANT.

APPLIGATION FILED JUNE so, 1909.

M JMM W@ J a .w MVV w 5 f M, @T 0 .L L

H. C. BEHR.

PNEUMATIG STAMPING PLANT.

APPLICATION FILED JUNE so, 1909.

1,034,863, Patented Aug. 6, 1912.

3 SHEETS-SHEET 3.

" The modern UNITED STATES PATENT OFFICE.

HANS CHARLES BEER, OF JOHANNESBUBG, TRANSVAAL.

VPNEUMIAIIC STAMPING PLANT.

Specification of Letters Patent.

To all whom it may concern:

Be it known that I, HANS CHARLES BEHR, a citizen of the United States ofAmerica, residing at Consolidated Goldfelds Building, Johannesburg,Transvaal, have invented new and useful Improvements in PneumaticStamping Plants, of which the following is a specification.

tendency to use continually heavier stamps for ore-crushing purposes andto accelerate their rate of operation has shown that the hithertogeneral method of operating them by means of cams and tappets hasreached its practical limit and that progress in the direction indicatednecessitates a radically different method of operation. The failureo-the cam and tappet device is primarily due to the difficulty ofdesigning the parts of sullicient strength to meet the conditionssuggested, the disproportionate augmentation of the shock of firstcontact between the cam and the tappet, and the speed limit introducedby the pause necessary to revent camming. To overcome this di culty,there has been developed the use as an actuating medium of elasticfluid, that is, for practical purposes, steam or compressed air. Theformer is wasteful whenused in a stamp, and for various reasons issomewhat unsuitable for use in most ore mills, in which environmentpneumatic stamps appear to be more suitable and have been used to' alimited extent. As hitherto constructed, however, pneumatic stamps havepresented serious drawbacks. In that type in which the air is usedsimply as cushions interposed bet-Ween the heads of a 'mechanicallyreciprocated cylinder and a piston to which the stamp head is attached,owing to the heating of the air, it is imperative constantly to permitsome of the heated air to escape at high pressure and to replace it fromthe atmosphere, thus-leading towaste of energy. In the other type ofpneumatic stamp which has been proposed, air is taken from theatmosphere, compressed and delivered to the cylinder of the stamp whereit does its work and whence it is exhausted back to the atmosphere. Incompressing air from atmospheric pressure-especially at highaltitudes-to a pressure suitable for practical purposes, by means of asingle stage compressor, an amount of heat is made sensible which wereit all retained in the air would raise its temperature to such an extentas to render its transmission to and use in the stamp cylinderimpracticable. It therefore becomes necessary to use a multi-stagecompressor which increases the cost of the plant and introducesmechanical complications; and also to abstract heat from the air whichinvolves 4the loss of the mechanical work by which it was produced.Again when such cooled air is usedlin the stamp cylinder, it 1simpossible to rexpand it through the same range within which it wascompressed, owing to the rapid fall of temperature, and consequentliability to freeze the moisture in the air. Energy is thus lost both incompression and inthe exhaust to an extent which renders the met-bod ofvtransmission very ineilicient. On the other hand, compressed air offersnndoubted advantages as a stamp actuating medium, especially 1n themanner in which it facilitates and extends the employment of electric,hydraulic and even in certain cases steam power; and it is the purposeof the present invention to provide a pneumatic stamping plant whichovercomes the drawbacks indicated above.

The nature ofthe invention may be indicated generally by describing itas a stamping plant operating upon the dense air system; z'. e. a systemin which the compressor and the engine form a closed circuit, air beingexhausted from the engine above atmospheric pressure and forming anartiticial dense atmosphere from which the compressor draws. Such asystem has already been applied to the actuation of pumps, rock drillsand winding engines situated at long distances from the compressor; butits application to a stamping plant is believed to be novel and usefulin that it is the only solution hitherto proposed for the practical andeicient actuation ofl stamps pneumatically.

A practical embodiment of the invention is shown in the accompanyingdrawings, in which- Figure I illustrates the complete system, Fig. II isan enlarged detail view of the stamp cylinder shown in Fig. I, and Fig.III a similar view of a double acting cylinder.

lReferring to the drawings, 1 indicates a mortar box, 2 the die thereinand 3 the stamp head. which passes -through the lower guide 4 andcarries lthe usual wearing shoe Patentediaug 6,1912.v Appnmoamed :uneso, 1909. serial No. 505,226.

sov

low said aperture is formed a transverse' slot 9 adapted toreceive anumber of shims such as 10. Said shims are formed at their lower edgeswith lugs to prevent lateral displacement of the packing pieces. anddies the end of the piston rod seats onto'the bottom of the slot 9; butas the shoes and dies wear the shims 10 are inserted from time to time.as required to maintain the piston rod 6 within its range of movement.The piston, or t e piston and the parts attached thereto, may beconsidered a pneumatic working element. It will be understood howeverthat any other suitable connection between the piston rod and the headmay be employed, such for example as forming the top of the head asgasplit nut which screws upon and is suitably clamped to thecorrespondingly threaded piston rod. y v

13 indicates the engine cylinder, the lower head 14 of which is securedto the girder 15, carried by the frames 16. Said lower head is extendedto form the upper guide for the stamp. The cylinderis packed internallyby a packing device 17 and externally by aA common gland 18.

19 is the piston to which therod 6 is secured and which works within thecylinder 13.

The engine shown in Figs. I and II is singlel acting, the stamp beingraised by compressed air and moving downward mainly by gravity.Referring to these figures, 20'indicates the high pressure `sup ly pipeby which air is conveyed to the engine and which is thickly lagged witha non-conducting coating 21; 22 1s the low pressure return pipe. Themain inlet valve 23 slides in a bore in with a seating 24 to cut offcommunication between a chamber 25 to which the high pressure inlet port26 opens, and the port 27 opening into the lower -end of the cylinder.Said valve 23 is forced downward by a Spring 28 bealng against acapQSh-gfdinto the upper end of the valve bore. 30 is the upper cylinderhead. 31 indicates a small by-pass valve by which high pressure air isadmitted under the main valve 23 to lift the same. Said by-pass valve isactuated by means of a cam 32 which engages a yoke 33 attached to thestem 34 of the valve, said cam being driven off a small constant speed11, adapted to co operate with corresponding depressions 12 formed inthe lower face of the slot 9,A andon the upper-edges of the shimsthemselves,

`. The valve is forced to When working with new shoes roperV air tightwith it by pac piston rod 6, in passing out of the thc cylinder wall andcontacts' motor 35. 36 indicates a port leading from the the valve 23.The exhaust valve 37 'is actuated by a second cam 38 which is gearedwith or otherwise caused to move in unison with, but in a differentphase from cam 32, Said cam 38 is shaped to give alonger opening to itsvalve than is cam 32. The spindle 39 passes through the stuffing box 40and makes contact with, but is separate from, the valve stem 41, so thatthe valve 37 is capable of lifting independently ofcam 38. its seat by alight indicated air exspring 42. As already cylinder bore to the upperend of \hausted by the open valve 37 passes awayl into pipe 22. 43 showsa connection from the low pressure line 22 to the upper end of thecylinder;l its openings 44 in the cylinder being somewhat below thehead30 to per-V mit cushioning in the upper end of the cylnder. The cylinder13 is provided with a false lower head 45 ,resiliently su ported uponsprings 46. Said head norma ly seats upon a shoulder 47 so as to closethe lower end of the cylinder, and the iston rod 6 is made king 48. Thespace 49 under said head '1s put 1nto communication with the highressure line 2O by means of a passage 50. n the lower face of the piston19 is raised the annular proection 51 and a correspondin recess 52 1sormed in the uppery face of t e head 45. The function of this false headis to yield resiliently incase the piston makes too long a downwardstroke, owing for example to the stamp head not being adjusted to thewear of the shoe and die. The piston acts on such headthrough aircushioned in the recess 52, so avoiding shock. v 53 indicatesa pair ofelectrical contacts in circuit with suitable signal means such as thelamp 54 and the bell 55. When the false head 45 is depressed .by thepiston it completes the circuit between said contacts, therebyindicating to the attendant that the stamp requires adjustment.

56 represents a single-stage compressor drivenforinstance by an electricmotor 57. l

Said compressor takes air from the low pressure line 22 and deliversinto the high pressure line 20.

A heater is shown diagrammatically at 58 inserted into the high pressureline 20. Similarly 59 indicates a means for coolin the return air. Suchcooling may be e fected by means of the mill water, which being therebywarmed and conveyed by a pipe 60 to the mortar box 1 is useful insoftening and quickening the amalgam within said mortar box or on theamalgamating plate 61. In other cases cyanid. solution may be 'used asthe coolin agent and being thereafter conveyed to the treatment vats itsheated state facilitates the treatment of the orc.

It is to be remarked that in actual praci tice,

p through glands and joints,

one compressor 56 with the heater 58 and cooler 59 would be arranged toactuate a grou of stamps, 'a controlling valve 62 beingv tted for eachstamp. All the valve gears of a number of stamps would preterably beoperated by onemotor 35, the cams of the several stamps being arrangedto produce the desired order of drop -when the stamps work in one mortarbox;

vFor achieving the requisite pressure throughout the system to beginwith, and for making up such leakage as 'may occur a small auxiliarycompressor 63 is arranged to force air drawn from the atmosphere intothe l'ow pressure line at the normal pressure existing inthe latter. Asshown, the auxiliary compressor is driven by air from the high pressureline 20 and exhausts such motive tiuid into the low pressure line 22.Its. operation is' controlled by a valve 64 which is closed by normalpressure of 4the air in the low pressure line 22 but when the pressurefalls below a predetermined point', is opened by a spring 65. Thus solong as said pressure is normal the auxiliary compressor is inoperative,but upon its decrease due to loss of air in the system, said compressoris automatically started.

66 indicates a spring controlled reliefv valve, which in the eventl ofpressure in the pipe 2O rising above the normal, permits the excess airto pass away to the low pressure line 22. Such increase of pressuremight be produced by overspeed of the main compressor 56, or by increasein the amount of heat supplied by the heater 58, or decrease of thatabstracted by cooler 59. Generally the leakage from the system willcompensate for any increase of pressure in the low pressure part ofthesystem, but as an emergency measure a relief valve 67 may be suppliedto relieve such excess pressure.

Overpressure ,in the return line may also be employed, to actuate aspeed regulating' device 68 for the motor 35 driving the valve gear; sothat the number of drops per minute of the stamps may be varied to suitany variation in speed'of the main compressor 56. Owing to theinefficiency of an elec,- tric mot-or when its speed is varied from thenormal, it is preferred to regulate the small motor 35 which' takes arelatively unimportant amount of current, rather than the largecompressor motor 57..`

The operation of the above described plant may be stated as follows, itbeing assumed that both the main and auxiliary compressors have been runfor suflicient time for normal conditions to be attained. Air at highpressure is delivered continuously by the compressor 56 In passingthrough the heater 58 it takes up a certain quantity of heat and itsvolume is increased. Assuming the piston 19 to be at into line 20.

the lower limit of its stroke, the small bypass valve 31 is momentarilylifted by its cam 32, thereby admitting high pressure air under the mainvalve 23 which is thus raised against the combined resistance of the lowpressure air above it and the spring 28. High pressure air is thusfreely admitted under and raises the piston 1,9. As soon as said pistonin .its upward travel uncovers port 36, high pressure air vpasses abovevalve 23 and by counterbalancing the high pressure beneath said valve,enables spring 28 to close'the same. Further admission being thus cutoff, the piston stroke is\continued by expansion of the air remaining inthe cylinden Immediately When, by reason of said expansion and themomentum of the stamp, pressure under the piston falls below that inthelow pressure line 22, valve 37 will open automatically. Cam 38 is sotimed that as quickly' as possible after such automatic opening of valve37, spindle 39 rises and retainsl said valve.

open during the downward stroke of the nston, permitting it to closeimmediately before the by-pass 31 re-opens for the next stroke. The useof the free exhaust valve obviates the lpossibility of theJ air pressurefalling too low during expansion and thus unduly retarding the piston.The air thus being exhausted, the' stamp falls by gravity, assisted bythe action of the low pressure air above it. Upon its upward stroke thepiston may traverse the opening 4/l'and thereby compress a cushion ofair in the upper end of the cylinder, from which it acquires an initialimpetus on its down stroke. The provision of said cushion compensatesfor the gradual loss of weight in the stamp due to wear of the shoe 3,since the less energy there is consumed in lifting the stamp, the morewill be available for accelerating the downward stroke. The low pressureair exhausted from the cylinder is conveyed to the cooler 59 where itstemperature and consequently its volume are reduced subst-antially tothose originally existing-and is then recompressed to undergo 'a furthercycle. Any air lost by leakage is made up hv the auxiliary compressor.

It is to be noted in regard to the addition and abstract-ion of heat toand from the system, that the heat added is utilized in the enginewithout appreciable loss, within the permissible range of .temperaturedetermined by its initial temperature and the ratio of expansionemployed. That portion of it which is reject/ed as low grade heat intothe cooling medium is also capable of etlicient ,employment for usefulpurposes closely related to the stamping of ore; so that the utilizationof energy in this manner becomes highly efficient. It. may be noted thatin a short closed air circuit such as that described, some cooling meansis desirable whether the air is directly heated or not, owing to thefact that as air is not an entirely perfect gas, repeated compressionscause a gradual accumulation of sensible heat in it. The present systempermits such heat to be removed Without simultaneous loss of pressureand. enables it to be applied to useful purposes.

Apart from the added heat and the comparatively small amount which isgenerated y the imperfection of the air as a gas and which is abstractedby the cooler, and also leakage losses, which the design permits ofbeing kept very low, the only difference in the work of the compressorand that expended by the stamp 1s that due to the re sistance of the'moving parts of the stamp and of the valves, ports and comparativelyshort system of pipes, so that the attainable efliciency of transmissionis high. The mechanical eliciency of a good compressor operating underconstant conditions is also high so that the total transmission from theprimary motor will be very eiiicient.

In F ig. III the air engine is shown double acting, air from the highpressure line being consumed to force the stamp downward. Theconstruction is generally similar to that of Figs. I and II, and thesame reference numerals apply, with the differences noted hereunder. Acylinder port 69, main inlet valve 70, cut off port 71, and exhaustvalve 72 are provided for the upper end of the cylinder similar to thosedescribed for the lower end. Both exhaust valves 37 and 72 are operatedby thev cam 38, by means of the pivotcd levers 73 and 74, the former ofwhich is connected directly to the yoke 75 and the latter indirectl bymeans of the link 76. Exhaust valve 772 opens to av branch 77 of the lowpressure line 22. The branch 43 shown in Fig. I leading om t-he lowpressure line 23 to the upper end of the cylinder is done away with andin lieu thereof, a branch 78 is taken from the high pressure line 20 toa chamber 79, communication of which with the upper end of the cylinderis controlled by a by-pass valve 80. having a stem 81 which projectsinto the path of the piston 19. Said valve is held to its seat by aspring 82 sufficiently strongly to obviate its lifting by fluidpressure. The method of operation in the upper end of the cylinder maybe exactly similar to that described in connection with the lower endexcept that the by-pass valve 80 is operated by the piston itselfinstead of by an independent cam. e action might however be modified ifdesired, by causing the upper exhaust valve 72 to close early so as toproduce compression in the upper cylinder end sufficient to open themain inlet valve 70 directly, the spring 83 of said valve being soadjusted that the valve will be forced open by a I both the exhaustedpressure somewhat less than that of the igh pressure line. The by-passvalve 80 may in this case be retained to serve as an emergency devicewhich would come into action in case the compression failed, for anyreason, to reach the requisite point.

From the foregoing descri tion it will be seen that the application ofpthe dense air system to the actuation of stamps presents a number ofadvantages. As compared with other devices of a similar nature, it willbe seen that a given difference between the inlet and exhaust pressuresmay be attained without the disadvantage of excessive variation voftemperature in the air which occurs when the same effective operatingpressure is obtained by compressing air from atmospheric pressure, andwhich tends both to over-heat the compressor and to freeze up the stampcylinder, A single stage compressor may thus, in the present system, beused efficiently and with small friction losses; while full expansion ispossible in the stamp cylinder. owing to the small change of volumerelatively to pressure, the expansion or compression part of the strokeis relatively small, the bulk of the stroke being pure displacement,leading to more uniform effort in the compressor and in the stampcylinder. For the same reason also the volume of air necessary totransmit a given power is relatively smaller, so that the plant iscorrespondingly more compact. A fur-` ther important feature is the easewith which heat may be applied directly to perform work; while thepossibility of cooling air before recompression enables cumulativeheating of the air by repeated compression to be more economicallyobviated, than in stamps of the pneumatic cushion type.

What I claim, ters Patent is l 1. In combination, a pneumatic motorcomprising a cylinder and piston, an air compressor, a high pressureconduit for conveying high pressure air from the compressor to themotor, a low pressure conduit for and desire to secure by Letconveyingexhaust air from the motor to the compressor, said motor, compressor andconduits forming a closed circulatory system in which the air moves in auniform direction, distributing valve mechanism interposed between thecylinder and the conduits for admitting air from the high pressureconduit to propel the piston and exhausting air from the cylinder intothe low pressure conduit to permit the return of the piston, and aseparate motor for actuating said distributing valve mechanism.

2. In combination, a fluid actuated motor, a source of supply of workingfluid, a fluid actuated main inlet valve controlling communicationbetween the source of supply and the motor, an auxiliary valve forcontrolling the opening of the main valve, and a. separate motor foroperating the auxiliary valve.

3. In a fluid actuated motor the combination with valve mechanismincluding a main induction port, a main inlet valve controlling thesame, an independently operated auxiliary valve -for admitting pressureto one end of the main valve to open to the saine and means controlledby the piston of the stamp for admitting pressure to the other side ofthe valve to cause cut off of the incoming air.

4:. In anexpansivel operating fluid actuated motor, Huid anission meansoperated and controlled independently of the moving member of saidmotor, and cut o means controlled by said moving member.

5. In combination, a fluid actuated motor, an air compressor, conveyingmeans forming with said motor and the compressor a closed circulatorysystem, distributing valve mechanism controlling admission to andexhaust from the motor, a separate motor for actuating said valvemechanism, and means the system for conmotor.

governed by pressure in trolling said last named 6. In a fluid actuatedmotor includin a cylinder and piston, distributing va ve mechanismincluding an' exhaust valve to exhaust fluid to permit return of the.piston and capable of opening automatically by difference of pressure,means forholding said valve in the open position of the'motor foractuating said last named means.

7. In combination, a cylinder includingx'a cylinder head, a piston, andsignal mec. anism including a contact device projecting inwardly fromthe cylinder head and adapted to be moved upon abnormal movement of thepiston to actuate a signal.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

HANS CHARLES BEHR.

adapted Witnesses:

H. OLDRoYD, WESLEY E. J oHN.

and means independent from the cylinder

